diff --git a/pkg/api/message/publish_test.go b/pkg/api/message/publish_test.go
index c5027240..a73bbc42 100644
--- a/pkg/api/message/publish_test.go
+++ b/pkg/api/message/publish_test.go
@@ -16,7 +16,7 @@ import (
 )
 
 func TestPublishEnvelope(t *testing.T) {
-	api, db, cleanup := apiTestUtils.NewTestAPIClient(t)
+	api, db, cleanup := apiTestUtils.NewTestReplicationAPIClient(t)
 	defer cleanup()
 
 	payerEnvelope := envelopeTestUtils.CreatePayerEnvelope(t)
@@ -64,7 +64,7 @@ func TestPublishEnvelope(t *testing.T) {
 }
 
 func TestUnmarshalErrorOnPublish(t *testing.T) {
-	api, _, cleanup := apiTestUtils.NewTestAPIClient(t)
+	api, _, cleanup := apiTestUtils.NewTestReplicationAPIClient(t)
 	defer cleanup()
 
 	envelope := envelopeTestUtils.CreatePayerEnvelope(t)
@@ -79,7 +79,7 @@ func TestUnmarshalErrorOnPublish(t *testing.T) {
 }
 
 func TestMismatchingOriginatorOnPublish(t *testing.T) {
-	api, _, cleanup := apiTestUtils.NewTestAPIClient(t)
+	api, _, cleanup := apiTestUtils.NewTestReplicationAPIClient(t)
 	defer cleanup()
 
 	clientEnv := envelopeTestUtils.CreateClientEnvelope()
@@ -96,7 +96,7 @@ func TestMismatchingOriginatorOnPublish(t *testing.T) {
 }
 
 func TestMissingTopicOnPublish(t *testing.T) {
-	api, _, cleanup := apiTestUtils.NewTestAPIClient(t)
+	api, _, cleanup := apiTestUtils.NewTestReplicationAPIClient(t)
 	defer cleanup()
 
 	clientEnv := envelopeTestUtils.CreateClientEnvelope()
diff --git a/pkg/api/message/subscribe_test.go b/pkg/api/message/subscribe_test.go
index 938f419b..e79c4cc9 100644
--- a/pkg/api/message/subscribe_test.go
+++ b/pkg/api/message/subscribe_test.go
@@ -70,7 +70,7 @@ func setupTest(t *testing.T) (message_api.ReplicationApiClient, *sql.DB, func())
 		},
 	}
 
-	return testUtilsApi.NewTestAPIClient(t)
+	return testUtilsApi.NewTestReplicationAPIClient(t)
 }
 
 func insertInitialRows(t *testing.T, store *sql.DB) {
diff --git a/pkg/api/payer/publish_test.go b/pkg/api/payer/publish_test.go
new file mode 100644
index 00000000..66bb1f60
--- /dev/null
+++ b/pkg/api/payer/publish_test.go
@@ -0,0 +1,127 @@
+package payer_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
+	"github.com/xmtp/xmtpd/pkg/api/payer"
+	"github.com/xmtp/xmtpd/pkg/envelopes"
+	blockchainMocks "github.com/xmtp/xmtpd/pkg/mocks/blockchain"
+	registryMocks "github.com/xmtp/xmtpd/pkg/mocks/registry"
+	"github.com/xmtp/xmtpd/pkg/proto/identity/associations"
+	envelopesProto "github.com/xmtp/xmtpd/pkg/proto/xmtpv4/envelopes"
+	"github.com/xmtp/xmtpd/pkg/proto/xmtpv4/payer_api"
+	"github.com/xmtp/xmtpd/pkg/registry"
+	"github.com/xmtp/xmtpd/pkg/testutils"
+	apiTestUtils "github.com/xmtp/xmtpd/pkg/testutils/api"
+	envelopesTestUtils "github.com/xmtp/xmtpd/pkg/testutils/envelopes"
+	"github.com/xmtp/xmtpd/pkg/utils"
+)
+
+func buildPayerService(
+	t *testing.T,
+) (*payer.Service, *blockchainMocks.MockIBlockchainPublisher, *registryMocks.MockNodeRegistry, func()) {
+	ctx, cancel := context.WithCancel(context.Background())
+	log := testutils.NewLog(t)
+	privKey, err := crypto.GenerateKey()
+	require.NoError(t, err)
+	mockRegistry := registryMocks.NewMockNodeRegistry(t)
+
+	require.NoError(t, err)
+	mockMessagePublisher := blockchainMocks.NewMockIBlockchainPublisher(t)
+
+	payerService, err := payer.NewPayerApiService(
+		ctx,
+		log,
+		mockRegistry,
+		privKey,
+		mockMessagePublisher,
+	)
+	require.NoError(t, err)
+
+	return payerService, mockMessagePublisher, mockRegistry, func() {
+		cancel()
+	}
+}
+
+func TestPublishIdentityUpdate(t *testing.T) {
+	ctx := context.Background()
+	svc, mockMessagePublisher, _, cleanup := buildPayerService(t)
+	defer cleanup()
+
+	inboxId := testutils.RandomInboxId()
+	inboxIdBytes, err := utils.ParseInboxId(inboxId)
+	require.NoError(t, err)
+
+	txnHash := common.Hash{1, 2, 3}
+
+	mockMessagePublisher.EXPECT().
+		PublishIdentityUpdate(mock.Anything, mock.Anything, mock.Anything).
+		Return(txnHash, nil)
+
+	identityUpdate := &associations.IdentityUpdate{
+		InboxId: inboxId,
+	}
+
+	envelope := envelopesTestUtils.CreateIdentityUpdateClientEnvelope(inboxIdBytes, identityUpdate)
+
+	publishResponse, err := svc.PublishClientEnvelopes(
+		ctx,
+		&payer_api.PublishClientEnvelopesRequest{
+			Envelopes: []*envelopesProto.ClientEnvelope{envelope},
+		},
+	)
+	require.NoError(t, err)
+	require.NotNil(t, publishResponse)
+	require.Len(t, publishResponse.OriginatorEnvelopes, 1)
+
+	responseEnvelope := publishResponse.OriginatorEnvelopes[0]
+	parsedOriginatorEnvelope, err := envelopes.NewOriginatorEnvelope(responseEnvelope)
+	require.NoError(t, err)
+
+	proof := parsedOriginatorEnvelope.Proto().Proof.(*envelopesProto.OriginatorEnvelope_BlockchainProof)
+
+	require.Equal(t, proof.BlockchainProof.TransactionHash, txnHash[:])
+}
+
+func TestPublishToNodes(t *testing.T) {
+	originatorServer, _, originatorCleanup := apiTestUtils.NewTestAPIServer(t)
+	defer originatorCleanup()
+
+	ctx := context.Background()
+	svc, _, mockRegistry, cleanup := buildPayerService(t)
+	defer cleanup()
+
+	mockRegistry.EXPECT().GetNode(mock.Anything).Return(&registry.Node{
+		HttpAddress: formatAddress(originatorServer.Addr().String()),
+	}, nil)
+
+	groupId := testutils.RandomGroupID()
+	testGroupMessage := envelopesTestUtils.CreateGroupMessageClientEnvelope(
+		groupId,
+		[]byte("test message"),
+		100, // This is the expected originator ID of the test server
+	)
+
+	publishResponse, err := svc.PublishClientEnvelopes(
+		ctx,
+		&payer_api.PublishClientEnvelopesRequest{
+			Envelopes: []*envelopesProto.ClientEnvelope{testGroupMessage},
+		},
+	)
+	require.NoError(t, err)
+	require.NotNil(t, publishResponse)
+	require.Len(t, publishResponse.OriginatorEnvelopes, 1)
+
+	responseEnvelope := publishResponse.OriginatorEnvelopes[0]
+	parsedOriginatorEnvelope, err := envelopes.NewOriginatorEnvelope(responseEnvelope)
+	require.NoError(t, err)
+
+	targetTopic := parsedOriginatorEnvelope.UnsignedOriginatorEnvelope.PayerEnvelope.ClientEnvelope.TargetTopic()
+
+	require.Equal(t, targetTopic.Identifier(), groupId[:])
+}
diff --git a/pkg/api/payer/service.go b/pkg/api/payer/service.go
index a25794d5..4c17c2fa 100644
--- a/pkg/api/payer/service.go
+++ b/pkg/api/payer/service.go
@@ -18,6 +18,7 @@ import (
 	"go.uber.org/zap"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
+	"google.golang.org/protobuf/proto"
 )
 
 type Service struct {
@@ -59,8 +60,8 @@ func (s *Service) PublishClientEnvelopes(
 
 	// For each originator found in the request, publish all matching envelopes to the node
 	for originatorId, payloadsWithIndex := range grouped.forNodes {
+		s.log.Info("publishing to originator", zap.Uint32("originator_id", originatorId))
 		originatorEnvelopes, err := s.publishToNodes(ctx, originatorId, payloadsWithIndex)
-
 		if err != nil {
 			s.log.Error("error publishing payer envelopes", zap.Error(err))
 			return nil, status.Error(codes.Internal, "error publishing payer envelopes")
@@ -73,6 +74,7 @@ func (s *Service) PublishClientEnvelopes(
 	}
 
 	for _, payload := range grouped.forBlockchain {
+		s.log.Info("publishing to blockchain", zap.Int("index", payload.originalIndex))
 		var originatorEnvelope *envelopesProto.OriginatorEnvelope
 		if originatorEnvelope, err = s.publishToBlockchain(ctx, payload.payload); err != nil {
 			return nil, status.Errorf(codes.Internal, "error publishing group message: %v", err)
@@ -80,7 +82,9 @@ func (s *Service) PublishClientEnvelopes(
 		out[payload.originalIndex] = originatorEnvelope
 	}
 
-	return nil, status.Errorf(codes.Unimplemented, "method PublishClientEnvelopes not implemented")
+	return &payer_api.PublishClientEnvelopesResponse{
+		OriginatorEnvelopes: out,
+	}, nil
 }
 
 // A struct that groups client envelopes by their intended destination
@@ -94,7 +98,7 @@ type groupedEnvelopes struct {
 func (s *Service) groupEnvelopes(
 	rawEnvelopes []*envelopesProto.ClientEnvelope,
 ) (*groupedEnvelopes, error) {
-	out := groupedEnvelopes{}
+	out := groupedEnvelopes{forNodes: make(map[uint32][]clientEnvelopeWithIndex)}
 
 	for i, rawClientEnvelope := range rawEnvelopes {
 		clientEnvelope, err := envelopes.NewClientEnvelope(rawClientEnvelope)
@@ -206,8 +210,26 @@ func (s *Service) publishToBlockchain(
 		)
 	}
 
+	unsignedOriginatorEnvelope := &envelopesProto.UnsignedOriginatorEnvelope{
+		OriginatorNodeId:     clientEnvelope.Aad().TargetOriginator,
+		OriginatorSequenceId: 0, // TODO: get this data from a full node
+		OriginatorNs:         0, // TODO: get this data from a full node
+		PayerEnvelope: &envelopesProto.PayerEnvelope{
+			UnsignedClientEnvelope: payload,
+		},
+	}
+
+	unsignedBytes, err := proto.Marshal(unsignedOriginatorEnvelope)
+	if err != nil {
+		return nil, status.Errorf(
+			codes.Internal,
+			"error marshalling unsigned originator envelope: %v",
+			err,
+		)
+	}
+
 	return &envelopesProto.OriginatorEnvelope{
-		UnsignedOriginatorEnvelope: payload,
+		UnsignedOriginatorEnvelope: unsignedBytes,
 		Proof: &envelopesProto.OriginatorEnvelope_BlockchainProof{
 			BlockchainProof: &envelopesProto.BlockchainProof{
 				TransactionHash: hash.Bytes(),
@@ -256,7 +278,7 @@ func shouldSendToBlockchain(targetTopic topic.Topic, aad *envelopesProto.Authent
 	case topic.TOPIC_KIND_IDENTITY_UPDATES_V1:
 		return true
 	case topic.TOPIC_KIND_GROUP_MESSAGES_V1:
-		return aad.TargetOriginator < constants.MAX_BLOCKCHAIN_ORIGINATOR_ID
+		return aad.TargetOriginator < uint32(constants.MAX_BLOCKCHAIN_ORIGINATOR_ID)
 	default:
 		return false
 	}
diff --git a/pkg/api/query_test.go b/pkg/api/query_test.go
index 54eb6957..c1499772 100644
--- a/pkg/api/query_test.go
+++ b/pkg/api/query_test.go
@@ -68,7 +68,7 @@ func setupQueryTest(t *testing.T, db *sql.DB) []queries.InsertGatewayEnvelopePar
 }
 
 func TestQueryAllEnvelopes(t *testing.T) {
-	api, db, cleanup := apiTestUtils.NewTestAPIClient(t)
+	api, db, cleanup := apiTestUtils.NewTestReplicationAPIClient(t)
 	defer cleanup()
 	db_rows := setupQueryTest(t, db)
 
@@ -84,7 +84,7 @@ func TestQueryAllEnvelopes(t *testing.T) {
 }
 
 func TestQueryPagedEnvelopes(t *testing.T) {
-	api, db, cleanup := apiTestUtils.NewTestAPIClient(t)
+	api, db, cleanup := apiTestUtils.NewTestReplicationAPIClient(t)
 	defer cleanup()
 	db_rows := setupQueryTest(t, db)
 
@@ -100,7 +100,7 @@ func TestQueryPagedEnvelopes(t *testing.T) {
 }
 
 func TestQueryEnvelopesByOriginator(t *testing.T) {
-	api, db, cleanup := apiTestUtils.NewTestAPIClient(t)
+	api, db, cleanup := apiTestUtils.NewTestReplicationAPIClient(t)
 	defer cleanup()
 	db_rows := setupQueryTest(t, db)
 
@@ -119,7 +119,7 @@ func TestQueryEnvelopesByOriginator(t *testing.T) {
 }
 
 func TestQueryEnvelopesByTopic(t *testing.T) {
-	api, store, cleanup := apiTestUtils.NewTestAPIClient(t)
+	api, store, cleanup := apiTestUtils.NewTestReplicationAPIClient(t)
 	defer cleanup()
 	db_rows := setupQueryTest(t, store)
 
@@ -138,7 +138,7 @@ func TestQueryEnvelopesByTopic(t *testing.T) {
 }
 
 func TestQueryEnvelopesFromLastSeen(t *testing.T) {
-	api, db, cleanup := apiTestUtils.NewTestAPIClient(t)
+	api, db, cleanup := apiTestUtils.NewTestReplicationAPIClient(t)
 	defer cleanup()
 	db_rows := setupQueryTest(t, db)
 
@@ -156,7 +156,7 @@ func TestQueryEnvelopesFromLastSeen(t *testing.T) {
 }
 
 func TestQueryTopicFromLastSeen(t *testing.T) {
-	api, store, cleanup := apiTestUtils.NewTestAPIClient(t)
+	api, store, cleanup := apiTestUtils.NewTestReplicationAPIClient(t)
 	defer cleanup()
 	db_rows := setupQueryTest(t, store)
 
@@ -177,7 +177,7 @@ func TestQueryTopicFromLastSeen(t *testing.T) {
 }
 
 func TestQueryMultipleTopicsFromLastSeen(t *testing.T) {
-	api, store, cleanup := apiTestUtils.NewTestAPIClient(t)
+	api, store, cleanup := apiTestUtils.NewTestReplicationAPIClient(t)
 	defer cleanup()
 	db_rows := setupQueryTest(t, store)
 
@@ -198,7 +198,7 @@ func TestQueryMultipleTopicsFromLastSeen(t *testing.T) {
 }
 
 func TestQueryMultipleOriginatorsFromLastSeen(t *testing.T) {
-	api, store, cleanup := apiTestUtils.NewTestAPIClient(t)
+	api, store, cleanup := apiTestUtils.NewTestReplicationAPIClient(t)
 	defer cleanup()
 	db_rows := setupQueryTest(t, store)
 
@@ -219,7 +219,7 @@ func TestQueryMultipleOriginatorsFromLastSeen(t *testing.T) {
 }
 
 func TestQueryEnvelopesWithEmptyResult(t *testing.T) {
-	api, store, cleanup := apiTestUtils.NewTestAPIClient(t)
+	api, store, cleanup := apiTestUtils.NewTestReplicationAPIClient(t)
 	defer cleanup()
 	db_rows := setupQueryTest(t, store)
 
@@ -237,7 +237,7 @@ func TestQueryEnvelopesWithEmptyResult(t *testing.T) {
 }
 
 func TestInvalidQuery(t *testing.T) {
-	api, store, cleanup := apiTestUtils.NewTestAPIClient(t)
+	api, store, cleanup := apiTestUtils.NewTestReplicationAPIClient(t)
 	defer cleanup()
 	_ = setupQueryTest(t, store)
 
diff --git a/pkg/envelopes/client.go b/pkg/envelopes/client.go
index 80178598..7ff94bb9 100644
--- a/pkg/envelopes/client.go
+++ b/pkg/envelopes/client.go
@@ -16,7 +16,7 @@ type ClientEnvelope struct {
 
 func NewClientEnvelope(proto *envelopesProto.ClientEnvelope) (*ClientEnvelope, error) {
 	if proto == nil {
-		return nil, errors.New("proto is nil")
+		return nil, errors.New("client envelope proto is nil")
 	}
 
 	if proto.Aad == nil {
diff --git a/pkg/envelopes/originator.go b/pkg/envelopes/originator.go
index 9a79cd08..76286bcd 100644
--- a/pkg/envelopes/originator.go
+++ b/pkg/envelopes/originator.go
@@ -15,7 +15,7 @@ type OriginatorEnvelope struct {
 
 func NewOriginatorEnvelope(proto *envelopesProto.OriginatorEnvelope) (*OriginatorEnvelope, error) {
 	if proto == nil {
-		return nil, errors.New("proto is nil")
+		return nil, errors.New("originator envelope proto is nil")
 	}
 
 	unsigned, err := NewUnsignedOriginatorEnvelopeFromBytes(proto.UnsignedOriginatorEnvelope)
diff --git a/pkg/envelopes/payer.go b/pkg/envelopes/payer.go
index c7ea76f3..22ec7183 100644
--- a/pkg/envelopes/payer.go
+++ b/pkg/envelopes/payer.go
@@ -17,7 +17,7 @@ type PayerEnvelope struct {
 
 func NewPayerEnvelope(proto *envelopesProto.PayerEnvelope) (*PayerEnvelope, error) {
 	if proto == nil {
-		return nil, errors.New("proto is nil")
+		return nil, errors.New("payer envelope proto is nil")
 	}
 
 	clientEnv, err := NewClientEnvelopeFromBytes(proto.UnsignedClientEnvelope)
diff --git a/pkg/envelopes/unsignedOriginator.go b/pkg/envelopes/unsignedOriginator.go
index 9d00a199..a98517e7 100644
--- a/pkg/envelopes/unsignedOriginator.go
+++ b/pkg/envelopes/unsignedOriginator.go
@@ -18,7 +18,7 @@ func NewUnsignedOriginatorEnvelope(
 	proto *envelopesProto.UnsignedOriginatorEnvelope,
 ) (*UnsignedOriginatorEnvelope, error) {
 	if proto == nil {
-		return nil, errors.New("proto is nil")
+		return nil, errors.New("unsigned originator envelopeproto is nil")
 	}
 
 	payer, err := NewPayerEnvelope(proto.PayerEnvelope)
diff --git a/pkg/indexer/e2e_test.go b/pkg/indexer/e2e_test.go
index 239d68af..2c76eed8 100644
--- a/pkg/indexer/e2e_test.go
+++ b/pkg/indexer/e2e_test.go
@@ -62,7 +62,7 @@ func TestStoreMessages(t *testing.T) {
 	groupID := testutils.RandomGroupID()
 	topic := topic.NewTopic(topic.TOPIC_KIND_GROUP_MESSAGES_V1, groupID[:]).Bytes()
 
-	clientEnvelope := envelopesTestUtils.CreateGroupMessageClientEnvelope(groupID, message)
+	clientEnvelope := envelopesTestUtils.CreateGroupMessageClientEnvelope(groupID, message, 0)
 	clientEnvelopeBytes, err := proto.Marshal(clientEnvelope)
 	require.NoError(t, err)
 
diff --git a/pkg/indexer/storer/groupMessage_test.go b/pkg/indexer/storer/groupMessage_test.go
index 5540b1f5..3499486c 100644
--- a/pkg/indexer/storer/groupMessage_test.go
+++ b/pkg/indexer/storer/groupMessage_test.go
@@ -49,7 +49,7 @@ func TestStoreGroupMessages(t *testing.T) {
 	message := testutils.RandomBytes(30)
 	sequenceID := uint64(1)
 
-	clientEnvelope := envelopesTestUtils.CreateGroupMessageClientEnvelope(groupID, message)
+	clientEnvelope := envelopesTestUtils.CreateGroupMessageClientEnvelope(groupID, message, 0)
 
 	logMessage := testutils.BuildMessageSentLog(t, groupID, clientEnvelope, sequenceID)
 	var err error
@@ -92,7 +92,7 @@ func TestStoreGroupMessageDuplicate(t *testing.T) {
 	message := testutils.RandomBytes(30)
 	sequenceID := uint64(1)
 
-	clientEnvelope := envelopesTestUtils.CreateGroupMessageClientEnvelope(groupID, message)
+	clientEnvelope := envelopesTestUtils.CreateGroupMessageClientEnvelope(groupID, message, 0)
 
 	logMessage := testutils.BuildMessageSentLog(t, groupID, clientEnvelope, sequenceID)
 
diff --git a/pkg/server/server_test.go b/pkg/server/server_test.go
index 4d00af06..6539e945 100644
--- a/pkg/server/server_test.go
+++ b/pkg/server/server_test.go
@@ -90,9 +90,9 @@ func TestCreateServer(t *testing.T) {
 	server2 := NewTestServer(t, server2Port, dbs[1], registry, privateKey2)
 	require.NotEqual(t, server1.Addr(), server2.Addr())
 
-	client1, cleanup1 := apiTestUtils.NewAPIClient(t, ctx, server1.Addr().String())
+	client1, cleanup1 := apiTestUtils.NewReplicationAPIClient(t, ctx, server1.Addr().String())
 	defer cleanup1()
-	client2, cleanup2 := apiTestUtils.NewAPIClient(t, ctx, server2.Addr().String())
+	client2, cleanup2 := apiTestUtils.NewReplicationAPIClient(t, ctx, server2.Addr().String())
 	defer cleanup2()
 
 	targetTopic := topic.NewTopic(topic.TOPIC_KIND_GROUP_MESSAGES_V1, []byte{1, 2, 3}).
diff --git a/pkg/testutils/api/api.go b/pkg/testutils/api/api.go
index 824f0adb..11862f84 100644
--- a/pkg/testutils/api/api.go
+++ b/pkg/testutils/api/api.go
@@ -24,7 +24,7 @@ import (
 	"google.golang.org/grpc/credentials/insecure"
 )
 
-func NewAPIClient(
+func NewReplicationAPIClient(
 	t *testing.T,
 	ctx context.Context,
 	addr string,
@@ -44,6 +44,25 @@ func NewAPIClient(
 	}
 }
 
+func NewPayerAPIClient(
+	t *testing.T,
+	ctx context.Context,
+	addr string,
+) (payer_api.PayerApiClient, func()) {
+	dialAddr := fmt.Sprintf("passthrough://localhost/%s", addr)
+	conn, err := grpc.NewClient(
+		dialAddr,
+		grpc.WithTransportCredentials(insecure.NewCredentials()),
+		grpc.WithDefaultCallOptions(),
+	)
+	require.NoError(t, err)
+	client := payer_api.NewPayerApiClient(conn)
+	return client, func() {
+		err := conn.Close()
+		require.NoError(t, err)
+	}
+}
+
 func NewTestAPIServer(t *testing.T) (*api.ApiServer, *sql.DB, func()) {
 	ctx, cancel := context.WithCancel(context.Background())
 	log := testutils.NewLog(t)
@@ -53,7 +72,7 @@ func NewTestAPIServer(t *testing.T) (*api.ApiServer, *sql.DB, func()) {
 	privKeyStr := "0x" + utils.HexEncode(crypto.FromECDSA(privKey))
 	mockRegistry := mocks.NewMockNodeRegistry(t)
 	mockRegistry.EXPECT().GetNodes().Return([]registry.Node{
-		{NodeID: 1, SigningKey: &privKey.PublicKey},
+		{NodeID: 100, SigningKey: &privKey.PublicKey},
 	}, nil)
 	registrant, err := registrant.NewRegistrant(ctx, log, queries.New(db), mockRegistry, privKeyStr)
 	require.NoError(t, err)
@@ -98,9 +117,9 @@ func NewTestAPIServer(t *testing.T) (*api.ApiServer, *sql.DB, func()) {
 	}
 }
 
-func NewTestAPIClient(t *testing.T) (message_api.ReplicationApiClient, *sql.DB, func()) {
+func NewTestReplicationAPIClient(t *testing.T) (message_api.ReplicationApiClient, *sql.DB, func()) {
 	svc, db, svcCleanup := NewTestAPIServer(t)
-	client, clientCleanup := NewAPIClient(t, context.Background(), svc.Addr().String())
+	client, clientCleanup := NewReplicationAPIClient(t, context.Background(), svc.Addr().String())
 	return client, db, func() {
 		clientCleanup()
 		svcCleanup()
diff --git a/pkg/testutils/envelopes/envelopes.go b/pkg/testutils/envelopes/envelopes.go
index 648d8a5e..883fa0af 100644
--- a/pkg/testutils/envelopes/envelopes.go
+++ b/pkg/testutils/envelopes/envelopes.go
@@ -42,12 +42,13 @@ func CreateClientEnvelope(aad ...*envelopes.AuthenticatedData) *envelopes.Client
 func CreateGroupMessageClientEnvelope(
 	groupID [32]byte,
 	message []byte,
+	targetOriginator uint32,
 ) *envelopes.ClientEnvelope {
 	return &envelopes.ClientEnvelope{
 		Aad: &envelopes.AuthenticatedData{
 			TargetTopic: topic.NewTopic(topic.TOPIC_KIND_GROUP_MESSAGES_V1, groupID[:]).
 				Bytes(),
-			TargetOriginator: 0,
+			TargetOriginator: targetOriginator,
 		},
 		Payload: &envelopes.ClientEnvelope_GroupMessage{
 			GroupMessage: &mlsv1.GroupMessageInput{